1. Field of the Invention
The present invention relates to a vehicle side frame subassembly wherein an upper hydro-formed rail and a lower hydro-formed rail are joined together by a plurality of pillars to form the side frame subassembly of the vehicle.
2. Background Art
Vehicle bodies require a frame to which body outer panels and other structural members are secured generally by welding. Vehicle frames are generally formed by welding together multiple sheet metal stampings that may be initially assembled as subassemblies. A large number of parts generally must be assembled together to form a side frame of a vehicle. Each part may vary to a limited extent in shape and dimensions as permitted by manufacturing tolerances. The problem with assembling a large number of parts together is that the dimensions of the final assembly may vary due to tolerance stack up.
Another problem with frame subassemblies manufactured from a large number of parts is that the cost of the assembly increases with part count due to the need to assemble and weld the multiple parts together. Also, substantial fixtures are required to hold the components of the frame together during assembly and welding operations. Large complex fixtures for manufacturing multi-part frame subassemblies add fixed costs to vehicle manufacturing facilities that are amortized over a number of vehicles manufactured with the tooling.
These and other problems and challenges are addressed by applicants' invention as summarized below.